Adding new dot shapes through sf.ps

This page applies to Harlequin v13.1r0 and later; both Harlequin Core and Harlequin MultiRIP.

The file sf.ps in the SW/Screens directory is used to store additional entries (beyond the built-in names) for the switchscreens dictionary. The contents of this file are added to switchscreens when the RIP starts. The file is run with switchscreens on the dictionary stack so the entries should provide a key for the internal name and a corresponding spot function procedure (which should be bound) or halftone dictionary followed by a def operator to insert them into switchscreens.

You should take care that the RIP is not running while the new entries are added to sf.ps.

For example, the following addition to the file would introduce a crude line screen into the system:

/CrudeLineScreen { pop } bind def

Note the use of the bind operator. The following would provide a simple 3x3 threshold screen:

TEXT

  /SimpleThreshold <<
        /HalftoneType 3
              /Width 3 /Height 3
              /Thresholds <E2 38 8D 55 1C FF A9 C6 71>
            >> def

These screens could then be selected with OverrideSpotFunctionName as follows, so that they would be used in place of any dot shape supplied by the job.

TEXT

            << /OverrideSpotFunctionName /CrudeLineScreen >> setsystemparams
            << /OverrideSpotFunctionName /SimpleThreshold >> setsystemparams

sf.ps contains special dot shape definitions for the Harlequin Screening Library. These dot shapes are used as place holder for the true arrangements of dots in the screen. They must not be modified.